4,4* Bismaleimido diphenylmethane

Other semi-2-IPNs [52] processed by the freeze-drying method included IPN from 4,4 -bismaleimido diphenylmethane (BMI) and linear BTDA/3,4 -ODA polyamic acid that were dissolved in 1,3,5-trioxane (Fig. 16). The resulting semi-2-IPNs exhibited higher Tgs and reduced phase separation, and contained no plasticizing solvent. A comparison of unidirectional properties of composites prepared by the freeze-dry process to those by traditional solvent evaporation process is presented in Table 13. The freeze-drying method for the preparation of IPNs appears to be superior to previous technology. 

Li Wanwan, Liu Feng, Wei Liuhe, and Zhao Tong. Allylated novolac/4, 4 -bismaleimido-diphenylmethane resin containing polyhedral oligomeric silsesquioxane Preparation, morphology and thermal stability. J. Appl. Polym. Sci. 104 no. 6 (2007) 3903-3908. 

---